Introduction

Calcium Oxide, commonly known as Quicklime or Lime, is a widely used inorganic alkaline compound and an important basic raw material in modern industry. It is extensively applied in metallurgy, construction and building materials, environmental protection, chemical processing, and agriculture-related processes.

Because of its strong basicity and high reactivity with water and carbon dioxide, Calcium Oxide plays an important role in processes such as steelmaking, cement production, flue gas desulfurization, wastewater treatment, and chemical manufacturing. At the same time, these properties require careful control during storage, transportation, and industrial handling.

What Is Calcium Oxide?

Calcium oxide (CaO), commonly known as quicklime or lime, is an inorganic alkaline compound that appears as a white or off-white powder at room temperature (though it may appear pale yellow or gray when impurities are present). It is one of the most widely produced and versatile basic inorganic chemical raw materials in the modern industrial system, playing an irreplaceable role in metallurgy, construction, environmental protection, chemical processing, and agriculture.

As a strongly basic oxide, calcium oxide is highly sensitive to water vapor and carbon dioxide. This characteristic forms the basis of its applications but also presents a critical risk that must be strictly controlled during storage and transportation. The market for calcium oxide continues to grow; according to industry reports, China’s consumption of calcium oxide has exceeded tens of millions of metric tons by 2025, and global demand is also rising steadily.

Key Properties of Calcium Oxide

Calcium Oxide is typically selected for its strong basicity, high-temperature stability, and reactivity with water, acids, and carbon dioxide. For reference, the key chemical and physical properties are summarized below.

Product Basic Information – Calcium Oxide

Calcium Oxide has a molecular weight of approximately 56.077 g/mol and a density of about 3.34 g/cm³ at 25°C. Its melting point is approximately 2572°C, while its boiling point is approximately 2850°C. Calcium Oxide is slightly soluble in water, where it reacts to form Calcium Hydroxide, and it is soluble in acids and glycerol.

Industrial Production Process

Modern calcium oxide production almost exclusively relies on the high-temperature calcination of limestone (calcium carbonate). The core process is as follows:

Raw Material Pretreatment: High-grade limestone (CaCO₃ content ≥95%) is carefully selected, then crushed and screened to the appropriate particle size (typically 40–80 mm).

Fuel and Proportions: Mixed with anthracite, coke, or natural gas (if solid fuels are used), with proportions calculated based on calorific value.

Kiln Calcination (Core Process): At temperatures of 900–1200°C, calcium carbonate decomposes upon heating:

CaCO₃ (s) → (high temperature) CaO (s) + CO₂ (g) ↑

Traditional Equipment: Vertical kilns (mixed-firing kilns), earthen kilns (now gradually being phased out)

Modern equipment: rotary kilns, fluidized-bed furnaces, and sleeve kilns, which offer precise temperature control, high product reactivity, and low energy consumption.

Cooling and Grading: The calcined lump quicklime is cooled, crushed, and ground to produce finished products of different mesh sizes (e.g., 200 mesh, 325 mesh), which are then shipped in packaged or bulk form.

Main Applications of Calcium Oxide

1.Metallurgical Industry (Largest Consumer, accounting for approximately 40%)

Used as a slagging agent in steelmaking: to remove impurities such as silicon, phosphorus, and sulfur from molten steel and improve the purity of the molten steel.

Used as a flux: to improve slag fluidity and protect the furnace lining.

Used in sintered ore production to improve blast furnace permeability.

2.Construction and Building Materials

A core calcareous raw material in cement manufacturing (comprising approximately 70% of cement clinker).

Used in the preparation of lime mortar and lime-based plastering materials.

Used in the production of new wall materials such as calcium silicate boards and aerated concrete blocks.

3.Environmental Protection Engineering (the fastest-growing sector)

Flue Gas Desulfurization (FGD): Used in wet desulfurization processes at power plants and steel mills to neutralize acidic gases such as SO₂ and HCl.

Acidic wastewater treatment: Adjusts pH levels and precipitates heavy metal ions.

Sludge conditioning and solidification: Improves sludge dewatering performance and reduces landfill volume.

4.Chemical Industry

Raw material for the production of calcium carbide (CaC₂) (CaO + 3C → CaC₂ + CO).

Production of soda ash (Solvay process) and bleaching powder (calcium hypochlorite).

Used as a solid desiccant for oils, alcohols, and ammonia (due to its strong hygroscopicity).

Hazards and Safety Operating Procedures (Must Be Taken Seriously)

Calcium oxide is classified as a Class 8 corrosive substance; it is strongly alkaline, highly hygroscopic, and exerts intense exothermic reactions. Improper handling may result in severe burns, fire, or even an explosion.

Key Safety Measures:

Personal Protective Equipment (PPE): Dust masks (N95 or higher), chemical-resistant safety goggles, acid- and alkali-resistant work clothes, and rubber gloves must be worn.

Storage Conditions: Store in a tightly sealed container in a dry, well-ventilated, fire-resistant warehouse. Mixing with water or acids is strictly prohibited. Stack height must not exceed 2 meters to prevent moisture absorption and caking.

Emergency Response: In case of skin contact, do not rinse directly with water (as the exothermic reaction may exacerbate injury); first wipe off the powder with a dry cloth, then rinse with plenty of running water for at least 15 minutes. If dust is inhaled, immediately move to fresh air and seek medical attention.

Fairsky: Calcium Oxide Manufacturing and Supply

FAIRSKY supplies Calcium Oxide for industrial applications requiring stable chemical composition and reliable processing performance. Depending on the intended application, Calcium Oxide can be supplied in different physical forms and particle or mesh sizes to better match customers' downstream processing requirements.

During production, limestone is carefully selected and processed before high-temperature calcination. The resulting quicklime is then cooled, crushed, and ground to produce finished products with different mesh sizes, such as 200 mesh and 325 mesh. Controlled processing and grading help maintain consistent material characteristics for industrial users.

FAIRSKY also supports international customers with product information, export documentation, logistics coordination, and professional communication, helping customers source Calcium Oxide for long-term industrial use.

Conclusion

Calcium Oxide remains an important basic inorganic chemical raw material used across metallurgy, construction, environmental protection, and chemical manufacturing. Its strong alkalinity, high-temperature stability, and reactivity with water, acids, and carbon dioxide make it suitable for processes ranging from steelmaking and cement production to flue gas desulfurization, wastewater treatment, and chemical synthesis.

For industrial users, selecting Calcium Oxide with stable composition, suitable particle size, controlled moisture, and consistent batch quality can help improve downstream processing efficiency and product stability.

With experience in chemical manufacturing and international supply, FAIRSKY provides Calcium Oxide products and supply solutions for customers in different industrial applications.